Verification that XProtect and Gatekeeper are up to date

I've searched around for an answer and it seems that Apple doesn't have a page that lists what the current versions of XProtect and Gatekeeper are. Also, it appears there's no notification on the client side when automatic security type updates are installed. Is this correct?

I'm aware of how secure OS X is. I'm just looking for a trustworthy source which lists what the versions should be at any point in time, for verification purposes.

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